A conventional data storage system typically includes front-end circuitry (e.g., a front-end server, a storage processor, a set of directors, etc.), a cache and enterprise-style disk drives (i.e., hard disk drives having platters designed to continuously rotate at extremely high speed for minimal latency). The front-end circuitry performs a variety of data storage operations (e.g., load and store operations) on behalf of one or more external clients by carrying out data access commands on the disk drives. During this operation, the cache temporarily buffers the exchanged data. In particular, a read portion of the cache temporarily holds data retrieved from the disk drives in the event that such data is needed again. Additionally, a write portion of the cache temporarily holds data written to the disk drives to enable the data storage system to acknowledge completion of write requests as soon as the write requests hit the cache under a write-back caching write policy.
Such a conventional data storage system is typically designed to operate at a peak state of readiness all the time. For example, the enterprise-style disk drives of the data storage system are directed to continuously spin their platters. In this peak state of readiness, the data storage system is always equipped to service requests immediately after receipt in the quickest manner possible.
Furthermore, such a conventional data storage system typically includes redundant disk drives (all of which have the same full operating speed) for fault tolerance. For example, the data storage system may implement RAID1 which involves simultaneously writing data to multiple disk drives. Accordingly, if one disk drive fails (e.g., becomes unavailable due to a head crash), the other disk drive remains available to provide the data.